Many studies have reported a significant association between childhood maltreatment and substance use. However, little is known about the precursors, natural history, or the true nature of this association. Prior studies of this association have mostly been cross-sectional, and could not define whether the association between childhood maltreatment and substance use is a direct, causal association, or whether maltreatment is a proxy for associated risk factors that lead to substance use, and/or whether the association is mediated by factors such as posttraumatic stress disorder (PTSD) and violence. We propose to evaluate these associations longitudinally using a data set from a large birth cohort. The Maternal Health Practices and Child Development (MHPCD) Project is a program of research on prenatal substance use and child outcomes. The proposed study cohort, the Teen Mother study (M. Cornelius, PI), consists of 404 low-income women who were teenage mothers and their children who participate in a study of prenatal exposure to tobacco. This cohort has been followed since the fourth prenatal month through the age of 10 years. Data have been collected on the development of the children, the home environment, and the social and emotional status of the mother during pregnancy, at birth, and at 6 and 10 years. These adolescents, by virtue of being offspring of teenage mothers with fewer resources and more chaotic lifestyles, are at increased risk for maltreatment, exposure to violence, and substance use. We will be able to look at predictors of substance use and of child maltreatment, as well as to control for concurrent covariates of the child maltreatment. At the 14- and 16-year assessments, we will measure the presence, timing, and characteristics of childhood maltreatment, and the onset, rates, and patterns of substance use among the offspring, as well as the current characteristics of the children, their mothers, and their environments, including exposure to violence. We will assess parental psychopathology, parental substance abuse, problems in the environment, and child developmental difficulties. We will complete a diagnostic evaluation for psychiatric disorders in the mothers and the offspring at ages 14 and 16. These data will allow us to identify risk factors for adolescent substance use, and to evaluate the roles that exposure to violence and PTSD may play in substance use. Moreover, these same data on the mothers will allow us to look at the effect of maternal childhood maltreatment, maternal substance use, and maternal PTSD, and the relations between these experiences and the subsequent substance use of the offspring. We can also evaluate and control for the effects of prenatal substance exposures on adolescent substance use. Thus, this cohort provides a unique opportunity to investigate critical questions about the relation between childhood maltreatment and substance abuse.